1. Field of the Invention
This invention relates to a device for separating a pair of electric contacts which tend to weld and consist of a stationary contact and a contact which is movable away from said stationary contact, particularly in a circuit breaker.
2. Description of the Prior Art
Pairs of contacts in switchgear are desirably made from a homogeneous noble material, preferably silver, in order to achieve good arcing properties and a low voltage drop across the contacts. But during a flow of short-circuit currents having a certain magnitude said material undesirably tends to effect a welding between the contacts. For this reason it is known to make the pairs of contacts from heterogeneous materials, such as sintered contacts, which will not tend to weld if they contain, e.g., carbon.
Such a risk of a welding of contacts will arise during a flow of a current below 400 amperes. During a flow of such a current in conventional switchgear a striking armature cannot yet be effective and the existing kinematic arrangement cannot separate the sticking contacts.
But the use of heterogeneous materials in such pairs of contacts has the disadvantage that they have poorer arcing properties. Besides, their use gives rise to considerable problems during the manufacture, particularly because a contact which has only a low tendency to weld can be mounted only with difficulty on a contact carrier.